By default, Censys performs full-text searches. For example, searching for
Dell will find any hosts where the word Dell appears in the
record—it won't limit the search to Dell manufactured devices. However, this is possible
by querying specific fields using the follow syntax:

Specifying Fields

Censys records are structured and allow
querying specific fields. For example, you can search for all hosts with a
specific HTTP status code with the following query: 80.http.get.status_code:
200. You can view a list of defined fields under the Data
Definitions tab or by looking at the details of a host.
For example, here are the fields for the Censys website.

Ranges

You can search for ranges of numbers using [ and ]
for inclusive ranges and { and } for exclusive
ranges. For example, 80.http.get.status_code:[200 TO 300].
Dates should be formatted using the following syntax: [2012-01-01
TO 2012-12-31]. One sided limits can also be specified:
[2012-01-01 TO *]. Warning!
The TO operator must be capitalized.

Wildcards and Regular Expressions

By default, Censys searches for complete words. In other words, the search
Del will not return records that contain the word Dell.
Wildcard searches can be run on individual terms, using ? to
replace a single character, and * to replace zero or more
characters. For example, if you want to search for words that start with
Del, you would search for Del*.

You can also search using regular expressions, e.g.,
metadata.manufacturer:/De[ll]/. The full regex syntax is available
here.

Boosting

The boost operator (^) can be used to
make one term more relevant than another. For example,
metadata.manufacturer: Dell^2 OR "Schneider Electric" places more
preference on the Dell keyword.

Reserved Characters

The following characters must be escaped with a backslash:
+-=&||><!(){}[]^"~*?:\/.